1. Field of the Invention
The present invention relates to crash-survivable enclosures for data memory units used in aircraft and other vehicles operating over land and water. More particularly, the invention is directed toward a crash-survivable enclosure which is capable of withstanding submersion to depths of up to 20,000 feet and high impact, shock, and mechanical penetration forces that commonly occur in a crash and the high temperatures, flames, and heat that often develop after a crash.
2. Description of the Prior Art
Solid state memory devices have been used in data recorders for recording essential data or information useful in determining causes of crashes or other mishaps in aircraft and other vehicles. When a crash occurs, it is essential that the recorded information on board survive the crash and subsequent events including heat, cold, flame, and fire that may afterwards ensue. In the event that the crash occurs over the ocean or other large body of water, the recorded information must be protected from the hydraulic pressure effects of deep water submersion.
Shielding the memory unit of a vehicle data recorder system during a crash, submersion, and/or a fire, for example, presents extremely demanding design constraints. Generally, it is desirable to protect voice and operational data supplied to the memory unit during a predetermined time interval immediately prior to a crash. In this regard, in order to preserve the data, the memory unit must be enclosed in a protective device configured and arranged to withstand temperatures in excess of 1,100.degree. C. (approximately 2,000.degree. F.) experienced during a fire and pressures up to 8,660 psi experienced at ocean depths of up to 20,000 feet. Simultaneously, the enclosure must be constructed to endure crushing and penetration forces experienced either on impact or during secondary impact with other portions or pieces of the vehicle.
Typical enclosures designed to meet these constraints are usually bulky, hemispherical enclosures, which have large space, weight, and power requirements. These extreme requirements generally prohibit the use of most crash-survivable enclosures in small vehicles such as, general aviation aircraft, railroad passenger/cargo cars, buses, or cargo trucks.
In view of these limitations, an enclosure is needed that is crash-survivable with a reduced size, a light weight, and a low power requirement.